In the mid-1980s, the United States was invaded. The invaders -- which mature into inch-long bivalves called zebra
mussels (Dreissena polymorpha) -- probably arrived as larvae in the
ballast water of a cargo ship from Europe. Within a few years, they had spread to all of the Great Lakes and into
the Illinois and Mississippi Rivers. A mature female produces as many as a million eggs per season. They are
still spreading.
Zebra mussel spread
 Mid 1980s
 1997
Extirpation of native mollusks
In Lake Erie -- the most adversely affected of
the Great Lakes -- zebra mussels have caused the loss of native species of mollusks unable to compete against this
aggressive invader.
Every year, fouling by zebra mussels costs utility
companies, port authorities, and local fisheries millions of dollars.
Encrusted intake pipe
The VW Beetle Experiment
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